United States highway 54 west from the east city limits of the city of Kingman to the west city limits of the city of Greensburg is hereby designated as the cannonball stageline highway. The secretary of transportation shall place highway signs along the highway right-of-way at proper intervals to indicate that the highway is the cannonball stageline highway, except that such signs shall not be placed until the secretary has received sufficient moneys from gifts and donations to reimburse the secretary for the cost of placing such signs. The secretary of transportation may accept and administer gifts and donations to pay for the cost of such highway signs bearing the proper approved inscription.